Browsing by Author "Tatam, Ralph P."

Combined shearography and speckle pattern photography for single-access multi- component surface strain measurement

Groves, Roger M.; James, Stephen W.; Tatam, Ralph P.; Fu, S. (International Society for Optical Engineering; 1999, 2003-12-31)

Full surface strain measurement requires the determination of two out-of-plane and four in-plane displacement gradient components of the surface strain tensor. Shearography is a full-field speckle interferometry technique ...

Compact methane sensor using an integrating sphere and interband cascade laser at 3313 nm

Davis, Nicholas M.; Francis, Daniel; Hodgkinson, Jane; Tatam, Ralph P. (Elsevier, 2023-04-23)

We present a sensor for gas detection utilising an integrating sphere and interband cascade laser for tunable diode laser absorption spectroscopy (TDLAS). Measurements were made of the methane absorption line at 3313 nm ...

Comparative signal-to-noise analysis of fibre-optic based optical coherence tomography systems

Ford, Helen D.; Beddows, R.; Casaubieilh, P.; Tatam, Ralph P. (Taylor & Francis, 2005-09-20)

Several optical coherence tomography ( OCT) systems are proposed using optical. fibre components and based around Fizeau sensing interferometers. The theoretical signal- to- noise ratio ( SNR) is calculated for each of ...

Composite material process monitoring using optical fibre grating sensors

Buggy, Stephen J. (Cranfield University, 2008-06)

In this thesis a long period grating (LPG) based sensor is investigated as a possible alternative to current process monitoring sensors used in the manufacture of composites to monitor cure. An LPG is demonstrated as a ...

Continous fibre optic components utilizing evanescent coupling to organic thin films

Charters, R. B. (Cranfield University, 1995-02)

The following thesis is conceded with single mode fibre optic components which exhibit a wavelength selective transmission response. The response is achieved by mechanically polishing the side of a optical fibre in ...

Correction of periodic displacement non-linearities by two-wavelength interferometry

Bridges, Angus; Yacoot, Andrew; Kissinger, Thomas; Humphreys, David A.; Tatam, Ralph P. (IOP, 2021-08-31)

Non-linearities in interferometric displacement measurements commonly affect both homodyne and heterodyne optical interferometers. Unwanted back reflections (ghost reflections) or polarisation leakage introduce non-linearity ...

Cost-effective vibration and displacement measurement using range-resolved interferometry

Kissinger, Thomas; Charrett, Thomas O. H.; James, Stephen W.; Tatam, Ralph P. (British Society for Strain Measurement’s (BSSM), 2015-09-03)

A recently developed range-resolved optical interferometric signal processing technique is applied to vibration and displacement sensing with fibre-based beam delivery. The technique is demonstrated to allow the simultaneous ...

Cryogenic Temperature Response Of Fibre Optic Long Period Gratings.

James, Stephen W.; Tatam, Ralph P.; Twin, Andrew; Bateman, Rod; Noonan, Paul (Iop Publishing Ltd, 2003-08-01)

The thermal response of the attenuation bands of an optical fibre long period grating was monitored over a temperature range of 4.2–280 K. A linear dependence of the central wavelength of the band, of gradient 0.2 nm K-1, ...

Cure monitoring of a UV cured epoxy resin using a long period grating Mach- Zehnder interferometer

Buggy, Stephen J.; Murphy, Richard P.; James, Stephen W.; Tatam, Ralph P. (International Society for Optical Engineering; 1999, 2007-12-31)

A cascaded long period grating Mach-Zehnder interferometer is used to monitor the change in refractive index of a UV cured epoxy resin over a cure cycle. Fourier techniques are used to calculate the phase shift and ...

Demodulation and de-multiplexing of a fibre Bragg grating sensor array using volume holograms

Reeves, Richard John (Cranfield University, 2009)

The demodulation of a Wavelength Division Multiplexed FBG sensor array by a matching array of holograms hosted within a Volume Holographic (VH) material is considered within this thesis. The FBG sensor elements possess ...

Design and fabrication of optical fibre long period gratings for CO₂ sensing

Barrington, James (2018-06)

This thesis investigated the repeatability of the overwrite long period grating (LPG) fabrication method and highlighted the advantage it offers in its ability to tune spectral features thus allowing the manufacture of ...

Design considerations for a three dimensional fiber optic laser Doppler velocimeter for turbomachinery applications

James, Stephen W.; Tatam, Ralph P.; Elder, R. L. (American Institute of Physics, 1997-12-31)

Single headed three dimensional (3D) laser Doppler velocimetry (LDV) geometries generally rely upon the use of three Doppler difference channels, inclined at differing angles with respect to the mechanical axes of the ...

Detection of volatile organic compounds (VOCs) using an optical fibre long period grating with a calixarene anchored mesoporous thin film

Korposh, Sergiy; Davis, Frank; James, Stephen W.; Wang, T.; Lee, Seung-Woo; Higson, Seamus P. J.; Tatam, Ralph P. (SPIE, 2013-05-06)

A long period grating (LPG) modified with a mesoporous film infused with a functional compound, calix[4]arene, was employed for the detection of volatile organic compounds (VOCs). The mesoporous film consisted of an inorganic ...

Determination of view vectors from image warping mapping functions

Nobes, David S.; Wieneke, B.; Tatam, Ralph P. (Spie -- the Int Soc for Optical Engineering, 2004-02-28)

The measurands of several reported laser-based measurement techniques are sensitive to both the propagation direction of the laser and the viewing direction from the region of interest to the detector. For such ...

Developing a proof of principle 3D-printed lab-on-a-disc assay platform.

Tothill, Alexander M. (2017-05)

A 3D-printed microfluidic lab-on-a-disc (LOAD) device was designed and manufactured using a low cost (˜£1600) consumer grade fused deposition modelling (FDM) Ultimaker 2+ 3D printer with imbedded microfluidic channels 1 ...

Development and application of optical fibre strain and pressure sensors for in-flight measurements

Lawson, Nicholas J.; Correia, Ricardo N.; James, Stephen W.; Partridge, Matthew; Staines, Stephen E.; Gautrey, James E.; Garry, Kevin; Holt, Jennifer C.; Tatam, Ralph P. (IOP Publishing, 2016-09-16)

Fibre optic based sensors are becoming increasingly viable as replacements for traditional flight test sensors. Here we present laboratory, wind tunnel and flight test results of fibre Bragg gratings (FBG) used to measure ...

Development of a pore pressure sensor employing fibre Bragg gratings

Gonçalves Correia, Ricardo Nuno (Cranfield University, 2008-12)

Monitoring pore pressure is important to understand and predict the mechanical behaviour of soil, helping engineers to assess the stability of slopes and built infrastructures. The instrumentation used to monitor pore ...

Development of an optical fibre pressure sensor for F1 applications.

Aime, Laura F. J. (Cranfield UniversitySATM, 2021-05)

This study investigated the development of optical fibre sensing technologies for the measurement of pressure in aerodynamic applications, in particular on F1 racing cars. The specific application placed constraints on ...

Development of shearography for surface strain measurement of non-planar objects

Groves, Roger M. (Cranfield University, 2001-12)

The subject of this thesis is the development of optical instrumentation for surface strain measurement of non-planar objects. The speckle interferometry technique of shearography is used to perform quantitative measurements ...

Development of the Cranfield University Bulldog Flight Test Facility

Lawson, Nicholas J.; Correia, Richardo N.; James, Stephen W.; Gautrey, James E.; Staines, Stephen E.; Partridge, Matthew; Tatam, Ralph P. (Cambridge University Press, 2017)

Cranfield University’s National Flying Laboratory Centre (NFLC) has developed a Bulldog light aircraft into a flight test facility. The facility is being used to research advanced in-flight instrumentation including fibre ...

Browsing by Author "Tatam, Ralph P."

Browsing by Author "Tatam, Ralph P."

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